1. Field
Provided are methods of manufacturing graphene, in which graphene is directly grown on a germanium layer or a germanium substrate.
2. Description of the Related Art
Graphene has electrical, mechanical, and chemical stability and excellent conductivity, and is thus noticed as a base material for electronic devices.
Graphene may be manufactured using a chemical vapor deposition (“CVD”) method or by pyrolyzing a silicon carbide (SiC) substrate.
However, when using the method of pyrolyzing a SiC substrate, it is difficult to manufacture large-sized graphene. In addition, since the SiC substrate is expensive, the economical efficiency in manufacturing graphene is low.
In the CVD method, a catalyst metal is used to manufacture graphene. Since graphene is planarly formed over a catalyst metal layer, the catalyst metal may be mixed in the graphene. However, it is difficult to remove the catalyst metal from the graphene. Also, it is difficult to remove the catalyst metal even by using a strong acid. A strong acid solution containing metal ions is used to remove the catalyst metal, but the graphene may be polluted due to the metal ions at this time.
Also, if the catalyst metal layer is a polycrystalline metal layer, the solubility of carbon is increased on a grain boundary, and a thickness of graphene on the grain boundary may increase accordingly. If the thickness of the graphene is not uniform, the properties of the graphene are influenced by the thickness of the graphene and thus, the synthesized graphene does not have uniform semiconductor characteristics, and it is difficult to use the above-described graphene to manufacture devices.